Building Brains 2 Flashcards
Define ‘pain’. (1)
An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage.
What is the difference between ‘nociception’ and ‘pain’? (2)
Nociception is the detection of noxious events in the environment.
Pain is the emotional response/feelings associated with nociception.
Name three types of afferent sensory nerve fibres in humans. (3)
A beta
A delta
C
Give the relative sizes of Ab, Ad, and C sensory fibres. (3)
Ab - Largest
Ad - Medium
C - Smallest
Which (if any) of the three sensory afferent nerve fibres in humans are myelinated? (3)
Ab and Ad are myelinated.
C are unmyelinated.
Describe the relative conduction velocities and thresholds for the three sensory afferent nerve fibres in humans. (6)
Ab - Fast conduction, low threshold
Ad - Fast conduction, medium-high threshold
C - Slow conduction, high threshold
Which neurotransmitter/s are released by A beta sensory fibres? (1)
Glutamate
Which neurotransmitter/s are released by A delta sensory fibres? (1)
Glutamate
Which neurotransmitter/s are released by C sensory fibres? (1)
Neuropeptides
(eg. substance P, CGRP, somatostatin)
Give the three ‘types’ or stimuli which can cause pain. (3)
- Thermal
- Mechanical
- Chemical
Which modalities do A beta sensory afferent fibres transmit? (3)
- Light touch
- Pressure
- Vibration
Which modalities do A delta sensory afferent fibres transmit? (3)
- Touch
- Temperature
- Sharp pain
Which modalities do C sensory afferent fibres transmit? (4)
- Noxious temperature
- Itch
- Significant pressure
- Dull pain
Describe ‘first pain’. (3)
- Neurones
- Localisation
- Time course
Carried by A delta fibres
Can be accurately localised because nerve endings are bunched together
Begins quickly (high conduction velocity) and goes away quickly (because glutamate rapidly removed from synapse)
Describe ‘second pain’. (3)
- Neurones
- Localisation
- Time course
Carried by C fibres
Location more generalised because nerve endings are spread out
Begins slowly (slow conduction velocity) and lasts longer (as neuropeptides slowly removed from synapse)
True or false (1):
A delta and C fibres are solely afferent neurones which transmit pain signals to the spinal cord.
False - they can have efferent roles too such as vasodilation and plasma extravasation
Which part of the spinal cord receives sensory information? (1)
Dorsal horn
Which dorsal horn laminae receive input from pain specific neurones? (1)
I and II
Which dorsal horn laminae receive input from touch specific neurones? (1)
III and IV
What is the role of lamina V of the dorsal horn? (1)
Integrates sensory input from all sensory neurone types.
True or false (1):
Although pain stimuli are processed by laminae I and II of the dorsal horn, laminae III and IV are also activated in response to a painful stimulus.
True - The touch neurones synapsing on laminae III and IV will also be activated because the high threshold stimulus will have surpassed the low threshold of A beta fibres.
Second order sensory neurones which relay pain signals to the brain mostly arise in which laminae of the dorsal horn? (2)
I and V
To which laminae of the dorsal horn does pain descending modulation usually project to? (1)
II
When first order sensory neurones enter the dorsal horn of the spinal cord, they can synapse onto which two general types of neurones? (2)
- Interneurones
- Projection neurones
Which laminae of the dorsal horn do A delta and C fibres synapse on? (1)
I, II, V
Which laminae of the dorsal horn do A beta synapse on? (1)
III, IV, V
Which lamina of the dorsal horn are A delta neurones MORE LIKELY to synapse on? (1)
a) I
b) II
I
Which lamina of the dorsal horn are C neurones MORE LIKELY to synapse on? (1)
a) I
b) II
II
What is the role of the spinoparabrachial tract in pain? (1)
Forms connections with the amygdala and basal ganglia to play a role in the emotional response to pain.
Apart from the amygdala and basal ganglia, name two other brain structures which may play a role in the emotional perception of pain. How do these structures receive their signals? (3)
Cingulate cortex and insula, which receive signals via the thalamus
How is the periaqueductal grey involved in pain? (1)
Provides descending pain modulation when stimulated.
Give six inputs to the PAG in the context of pain. (6)
- Prefrontal cortex (cingulate and insula)
- Spinal cord dorsal horn
- Amygdala
- Nucleus accumbens
- Hypothalamus
- Locus coeruleus
Which part of the PAG organises descending modulation of pain systems? (1)
Ventrolateral
Which part of the PAG organises autonomic functions? (1)
Dorsolateral
Which part of the PAG projects to the thalamus and frontal cortex as part of the ascending pain pathways? (1)
Rostral
From which sensory fibres does the ventrolateral PAG receive most of its input? (1)
C
From which sensory fibres does the dorsolateral PAG receive most of its input? (1)
A
Describe the descending pain pathway from PAG to spinal cord. (3)
- Ventrolateral PAG
- Rostral ventral medulla (also called nucleus raphe magnus)
- Spinal cord dorsal horn
Describe two ways in which descending signals from the PAG can modulate pain pathways. (2)
- Postsynaptic inhibition of dorsal horn neuronal activity
- Presynaptic inhibition of NT release from nociceptors
Which neurotransmitters can be used in the descending pain pathways? (3)
- Opioids
- Serotonin
- Noradrenaline
What is ‘hyperalgesia’? (1)
Increased responsiveness to a normally noxious stimulus.
What is ‘allodynia’? (1)
Pain or unpleasant sensation evoked by normally non-painful stimulation.
What is ‘spontaneous pain’? (1)
Pain with no obvious immediate cause.
Describe primary hyperalgesia. (4)
Peripheral neuronal changes
to thermal and mechanical stimuli
over a small area surrounding injury
which occurs quickly.
Describe secondary hyperalgesia. (4)
Central nervous system changes
to mechanical stimuli
over a large region surrounding injury
which occurs over a longer period of time.
Describe the effect of intensity and unpleasantness of pain perceived by somebody with a bad mood. (2)
Intensity remains the same but unpleasantness increases.
Describe the effect of intensity and unpleasantness of pain perceived by somebody who is paying less attention/is distracted. (2)
Intensity decreased but unpleasantness is the same.
Which cortical structure is generally regarded as the place where emotional and conscious perceptions of pain are integrated? (1)
Insular cortex
Are limbic system structures cortical or subcortical? (1)
Mixture of both
Give two general roles of the limbic system. (2)
- Respond to emotional, social, and motivational stimuli
- Learning and memory
What are the three components of an ‘emotional state’? (3)
- Autonomic responses
- Subjective feelings
- Cognition
Name the four cortical components of the limbic system. (4)
- Cingulate gyrus
- Parahippocampal gyrus
- Orbitofrontal cortex
- Sensory association areas
Name the 10 subcortical components of the limbic system. (10)
- Amygdala
- Stria terminalis
- Hypothalamus
- Anterior nucleus of the thalamus
- Septal nuclei
- Olfactory bulbs
- Hippocampus
- Fornix
- Nucleus accumbens
- Mammillary bodies
Which lobe contains both the amygdala and the hippocampus? (1)
Temporal lobe
When looking at brain slices, how do you tell the difference between the amygdala and the hippocampus? (2)
The amygdala is smaller and sits more anteriorly.
Name the two main white matter structures connecting the limbic system. (2)
- Fornix
- Stria terminalis
Describe how the hippocampus is connected to other structures in the limbic system. (4)
Connected to mammillary bodies
via the fornix
the mammillary bodies then connect to the anterior thalamus
via the mammillothalamic tract.
Describe the role of the stria terminalis. (3)
Connects the amygdala
to the hypothalamus
and nucleus accumbens.
What is the role of the septal nuclei in the limbic system? (1)
They regulate hypothalamic aggression.
What is the role of the cingulate gyrus in the limbic system? (1)
Cognitive, attentional, and emotional processing.
Give three roles of the hypothalamus relating to the limbic system. (3)
- Autonomic functions (can be related to emotion)
- Endocrine functions
- Aggression
What are the roles of the amygdala in the limbic system? (4)
- Recognising fear
- Acquiring a new fear
- Producing fear responses
- Subjective experience of emotions and pleasure